The present invention relates to an arrangement for making contact between the conductor tracks of printed circuit boards with contact pins which are inserted into bores of the printed circuit boards and which are electrically conductively connected with the conductor tracks by means of bodies formed of solder material, arranged at the region of the locations where contact is to be made, by the infeed of heat.
In devices of the telecommunication and data processing art there are used at the present time so-called rear wall printed circuit boards. These single or also multilayer plates constitute printed circuits which are employed in frames at the rear wall and at which there are applied connections in the form of conductor tracks which are present between the structural groups equipped with components and mounted in the frame. Furthermore, these plates are employed for intermeshing the supply voltages and the reference potential. A rear wall printed circuit board possesses a multiplicity of multipoint connectors whose contact pins arranged in rows piercingly extend through holes provided at the rear wall printed circuit board and are electrically conductively connected with the conductor tracks. The structural groups are mounted in the frame by being fitted on to such multipoint connectors. The contact pins protruding out of the rear wall printed circuit board at the rear side of the frame render possible in a simple manner, the establishment of additional connections between certain circuit points, for instance according to known solderfree techniques, such as winding, crimp or clamp connections.
There exists the problem of reliably making contact in the most rational manner between the numerous contact pins of such multipoint connectors with the plug points at the rear wall printed circuit board, i.e. establishing a faultless electrical connection between the contact pin and the conductive material at the printed circuit board. It is not possible to employ an individual soldering according to conventional techniques, since, on the one hand, with the multiplicity of points where contact should be made there is no longer possible any rational mode of operation, and on the other hand, the spacing between the individual contact pins, which becomes increasingly smaller with the continuously progressive miniaturisation, renders questionable a reliable contact making between the individual contact pins. Equally contact making by means of a solder bath is not possible since in doing so the contact pins themselves are coated with the solder in an undesired manner. For overcoming these difficulties there has been proposed in German Patent Publication No. 2,257,003 an apparatus for making contact between conductor tracks extending upon a printed circuit board and contact elements, wherein there is provided a radiation source such as, for instance, a halogen lamp whose radiation thermal energy is infed to the contact locations provided with a soldering agent. The focusing and infeed of the thermal radiation to the contact locations is accomplished with focusing means, and additionally there is provided a transport device which successively brings the locations where the contact is to be made at the printed circuit board into the operable range of the radiation source for a certain period of time. With this equipment it is only possible to simultaneously solder one contact location, which requires an appreciable expenditure in time when encountering a large number of contact locations. A further unfavorable circumstance which exists with such apparatus resides in the fact that particularly in the case of small spacing of the contact locations there is not only undertaken heating of the desired contact location, but also there can arise heating at its direct surroundings and thus, possibly their extending conductor tracks as well as the carrier material of the printed circuit boards can become adversely affected.